Many machine tools are configured so that workpieces are machined in an internal area closed by a cover, thereby securing the security. Although the cover has a window, an operator can visually recognize only a limited portion through this window, and therefore, there is a limitation in monitoring the machining status of a workpiece.
Therefore, as described in the Japanese Unexamined Patent Application Publication No. 2005-190102, for example, a camera is arranged in the internal area in the machine tool and images obtained from this camera are displayed on the display device, thereby the operator can check the machining status of a workpiece with the displayed images.